This project consists of a broad, neurophysiological and neuroanatomical examination of the corticocortical connections of the sensorimotor cortex and their role in primate motor behaviors which rely upon sensory input. Four questions were selected for initial study. First, the influence of the densest of the corticocortical inputs to the primary motor cortex (MI) is being examined by making reversible cooling lesions of the primary somatic sensory cortex (SI) and posterior parietal cortex (area 5), while recording the response of single neurons in the MI cortex to somatic sensory stimulation. Second, the responsiveness of neurons in the primary motor cortex and the supplementary motor cortex (MII), which both receive dense corticocortical inputs from somatic sensory areas of the cortex, is being directly compared in the alert, behaving monkey. Third, the precise responsiveness of neurons in area 3a, the "transition" cortex between MI (precentral cortex) and SI (postcentral cortex), to somatic sensory stimulation and the extent of its corticocortical projection to MI is being investigated. Fourth, the efferent connections of MII, especially its corticocortical and corticothalamic projections, are being examined in an effort to determine the extent to which these connections differ from those of MI.